1. Field of the Invention
The present invention relates to a shielded connector for connecting a braided covering of a shielded wire to a metallic case of an apparatus so that the braided covering can be grounded. More particularly, the present invention relates to a shielded connector, the structure of which is simple so that the assembling work can be simplified and further the shielding property and the reliability of connection can be enhanced.
2. Description of the Related Art
In order to shut off electric noises such as electromagnetic waves and static electricity, there is provided a shielded electric wire to be used as a high-tension electric wire composed in such a manner that a core covered with and insulated by an inner covering is further covered with a braided covering, and furthermore the braided covering is covered with a sheath for insulation.
In order to connect the braided covering of the shielded wire to a metallic case of an apparatus so that the braided covering can be grounded, a special shielded connector has been conventionally used.
First of all, a shielded connector of a first conventional example, which is disclosed in Japanese Utility Model Unexamined Publication No. Hei. 6-58560, will be described below.
FIG. 5 is a cross-sectional view showing a shielded connector of the first conventional example.
In FIG. 5, reference numeral 1 is a shielded electric wire, which includes a core 1A, an inner covering 1B for covering and insulating the core 1A, a braided covering 1C for covering the outside of the inner covering 1B, and a sheath 1D for covering and insulating the braided covering 1C.
At an end portion of the shielded electric wire 1, the inner covering 1B and the sheath 1D are peeled off stepwise, so that the core 1A and the braided covering 1C are exposed.
The end portion of the shielded electric wire 1 composed as described above is attached to a metallic case 2 of an apparatus (not shown) via a shielded connector 100.
An outline of the structure of the shielded connector 100 is described as follows. A connector housing 104 is made of synthetic resin, and a cylindrical metallic shell 101 is insert-molded to the connector housing 104. Further, a terminal metal fitting 105, a connecting member 103 and a rubber plug 102 are accommodated in the connector housing 104.
On an outer circumference of the connector housing 104, there are provided flanges 104a, 104a which are formed integrally with the connector housing 104. In each flange 104a, there is provided a bolt hole for directly attaching the connector housing 104 to the metallic case 2.
In the metallic shell 101, there are provided contact pieces 101a, 101a corresponding to the flanges 104a, 104a. When the connector housing 104 is directly attached to the metallic case 2, these contact pieces 101a, 101a are electrically connected to the metallic case 2.
The core 1A of the shielded electric wire 1 is connected to one side of the terminal metal fitting 105, and an electric wire of the apparatus is connected to the other side of the terminal metal fitting 105.
The terminal metal fitting 105 described above is fixed to the connector housing 104 by a stop ring 107.
The connecting member 103 is formed into a ring-shape which coincides with a profile of the rubber plug 102. The connecting member 103 is press-fitted into the braided covering 1C, so that the braided covering 1C can be connected to the metallic shell 101.
The rubber plug 102 is provided for ensuring the water-tightness in the connector housing 104. The rubber plug 102 is fixed to the connector housing 104 by a rubber plug holder 106.
In the shielded connector 100 composed as described above, when the connector housing 104 is directly attached to the metallic case 2, the metallic shell 101 can be connected to the metallic case 2 via the contact pieces 101a, 101a.
Due to the foregoing, the braided covering 1C of the shielded electric wire 1 connected to the metallic shell 101 via the connecting member 103 is grounded to the metallic case 2.
Next, a shielded connector of a second conventional example will be described below which is disclosed in Japanese Patent Unexamined Publication No. Hei. 8-96868.
FIG. 6 is a cross-sectional view showing a shielded connector of the second conventional example.
In FIG. 6, an outline of the structure of a shielded connector 200 is described as follows. A rubber plug 202, a connector housing 203 made of synthetic resin and a spring piece 204 are successively inserted into a cylindrical metallic shield cap 201 which corresponds to the metallic shell 101 described above. A metallic shield ring 205 is attached to a braided covering 1C of a shielded electric wire 1.
In the shield cap 201, there is provided a flange 201a. The shield cap 201 is directly attached to a metallic case 2 of an apparatus (not shown) by fixing the flange 201a with bolts.
In the shielded connector 200 described above, when the shield ring 205 attached to the braided covering 1C of the shielded electric wire 1 is connected to the shield cap 201 via the spring piece 204, the braided covering 1C is grounded to the metallic case 2 of the apparatus.
However, the following problems may be encountered in the conventional shielded connectors 100 and 200 described above. The number of parts of the shielded connector of each conventional example is large, and further the structure is complicated. Therefore, it takes much time to assemble the conventional shielded connector. Furthermore, the shielding property of the conventional shielded connector is deteriorated.
In the shielded connector 200 of the second conventional example, the shield cap 201 and the connector housing 203 made of synthetic resin are formed separately from each other . Therefore, the number of parts is increased and further the number of steps required for assembling the shielded connector is increased.
On the other hand, in the shielded connector 100 of the first conventional example, the metallic shell 101 is insert-molded to the connector housing 104 made of synthetic resin. However, according to the above structure, the connector housing 104 and the metallic shell 101 must be press-formed separately from each other. As a result, the number of parts is increased and further the number of steps required for manufacturing the shielded connector is increased.
In the shielded connector 100 of the first conventional example, it is difficult to press-fit the shielded electric wire 1 into the connecting member 103 so that the braided covering 1C of the shielded electric wire 1 is not twisted. On the other hand, in the shielded connector 200 of the second conventional example, it is difficult to insert the shielded electric wire 1 into the shield ring 204 so that the braided covering 1C of the shielded electric wire 1 is not twisted. In both of the first and second conventional examples, skilled technique is required for assembling work of the shielded connector.
Further, in the shielded connector 100 of the first example and the shielded connector 200 of the second example, the structure is so complicated that it is impossible to assemble the shielded connector in such a manner that the shielded electric wire 1 is simply inserted into the parts composing the shielded connector and pushed into the connector housing 104 or 203.
In addition to that, when the connecting member 103 or the shield ring 205 is assembled to the braided covering 1C of the shielded electric wire 1, there is a possibility that the braided covering 1C is twisted. In this case, the contact becomes defective, and the shielding property is deteriorated.